The present invention generally relates to telecommunication systems and more particularly to a transfer of push-button signals from a terminal to a service system via an exchange.
Conventionally, it is practiced to provide various services such as reservation of air tickets, collection of questionnaires, and the like, by transferring push-button signals created by a push-button telephone set or a personal computer having an equivalent function to an appropriate service system.
FIG. 1 shows the construction of a conventional transfer system of push-button signals.
Referring to FIG. 1, an exchange 10 carries out a switching of a network (NW) 11 and accommodates therein a line to an end user terminal 12, which may be a push-button telephone or a personal computer having an equivalent function. The exchange 10 further includes a push-button signal receiver (PBR) 14 for detecting push-button signals supplied from the end user terminal 12 to the exchange 10, wherein the push-button signal receiver 14 further converts the detected push-button signals to a corresponding code. As a result of the foregoing conversion, the address (telephone number) of the destination terminal is recognized when a call is issued by the end user terminal 12.
Further, it should be noted that the network 11 is connected to a service system (SS) 16 that provides various services such as reservation of air tickets or collection of questionnaires. The network 11 may use a common-line transmission process in which various monitoring and control signals are transmitted through a common signal line 18. For the transmission of an audio signal, an audio-channel 20 is provided. It should be noted that the exchange 10 and the service system 16 are connected to the audio-channel 20 via trunks (TRK) 21 and 22. Further, the service system 16 also includes a push-button signal receiver (PBR) 24.
In operation, a push-button signal issued by the user at the terminal 12 during a state in which there is a circuit connection between the end user terminal 12 and the service system 16, is transferred to the service system 16 from the exchange 10 to the audio-channel 20, wherein the push-button signal receiver 24 of the service system 16 detects the push-button signal and converts the same into a corresponding code.
In such a conventional system, in which the exchange 10 accommodates therein the line to the end user terminal 12, it is essential that the exchange 10 has the push-button signal receiver 14 for detecting the destination address supplied from the end user terminal 12 at the time of setting up a call in the form of push-button signals and for converting the push-button signals to a corresponding code. On the other hand, the conventional system of FIG. 1, in which the push-button signals are transmitted through the audio-channel 20, has required the service system 16 to have the push-button signal receiver 24 also in addition to the push-button signal receiver 14, for detecting the push-button signals transmitted through the audio-channel 20 and for converting the same to a corresponding code. Thereby, there has been a problem in the conventional system of FIG. 1 that the cost of investment is excessive.
Further, in the conventional system of FIG. 1, there has been a problem in that the push-button signal, supplied by the end user at the terminal 12 and transmitted through the audio-channel 20, may experience attenuation as it is propagated through the audio-channel 20 for a long distance. Thereby, there is a substantial risk hat the transmittance of the push-button signals is impaired and the chance of erroneous reception at the service system 16 is increased.